Rail transportation systems are well known and widely used in most areas of the world, due to their relative efficiency in the carriage of goods and people over a distance. However, rail transportation is limited in the size and weight of the freight or cargo which can be carried, due to the size (particularly the width) of the rolling stock; the rolling stock in turn is limited by the gauge of the track being used.
As a result of the above limitation, larger and heavier shipments are commonly conveyed by sea, or transported by air in specialized aircraft in some instances. The alternative is to break down the larger article into smaller components which may be carried by rail. This is commonly done particularly with bulk goods, where they are removed from a bulk carrier ship or barge and loaded aboard a train of bulk carrier rolling stock for shipment by rail.
This of course results in much additional labor in the transfer of such goods and cargo from one form of transport to another, which raises the shipment and energy costs involved. While attempts have been made to increase the capacity of the rolling stock used in rail transportation, there are ultimate limits due to the standard gauge used and the resulting maximum car width practically attainable in order to maintain reasonable stability of the load. Wider gauge tracks are not the answer, as there would stills be only two rails to handle the resulting additional weight. However, many, if not most, rail lines have duplicate track systems to allow for the passage of trains traveling in opposite directions, and for other reasons. With the advent of modern communications and control systems, many of these double track lines are redundant, as multiple trains may be scheduled and controlled to make the use of a single track practical, with the use of sidings and such. Accordingly, two adjacent parallel tracks comprising a total of four rails (or more generally, X number of adjacent parallel tracks comprising a total of 2X rails) may be used for the transport of greater than standard width freight and other articles, with the proper equipment.
The need arises for a rail transportation system which makes, use of multiple track systems, either existing or specially constructed, for the transport of wider and heavier than standard freight. Rolling stock must be provided which is compatible with such a multiple track system, as well as coupling and other systems to enable such multiple track rolling stock to be used in combination with standard rolling stock and locomotives.